A programmable logic device, such as field programmable gate array (FPGA) or a complex programmable logic device (CPLD), may be used in a variety of applications. A programmable logic device (PLD) offers the advantage of being reprogrammable in the field (e.g., while on the circuit board in its operational environment).
A drawback of a conventional PLD is that, while its configuration memory is being reprogrammed, the PLD typically cannot preserve data stored in its volatile memory (e.g., volatile embedded random access memory (RAM) blocks) and, consequently, the data is lost during the reprogramming process. However, depending upon the particular application, a user of the PLD may prefer to preserve the data stored in the volatile memory for use within the PLD after the reprogramming (i.e., reconfiguration) of the PLD has been completed and the PLD is operating based upon the new configuration data provided during the reprogramming.
Furthermore, a conventional PLD generally does not provide reprogrammable non-volatile memory that a user can directly access for storing desired user information. Thus for example, the conventional PLD would first have to be configured to programmably provide direct user access to the non-volatile memory for storing the desired user information. As a result, there is a need for improved memory and reconfiguration techniques for PLDs.